Hydraulic transmission



July 28, 1925.

M. J. B. CACAUD HYDRAULICl TRANSMISSION July 28, 1925. 1,547,409

M. J. B. cAcAuD HYDRAULIC TRANSMISSION FiledDeC`.' 2. 1922 2 Sheets-Sheet 2 Patented July 28, 1925.

1,547,409l PATENT porrlcE.

f MARCEL JEANEENJAMIN CACAUD, OF TOULON, FRANCE, ASSIGNOR OF ONE-HALF TO SOCIETE ANONYME DES FORGES ET CHANTIERS DE LA MEDITERRANEE, OF PARIS,

FRANCE, A. CORPORATION OF FRANCE.

HYDRAULIC TRANSMISSION.

Application led December 2, 1922'. Serial No. 604,601.

To all whom it 'may concern.'

Be it known that I, MARCEL JEAN BEN- JAMIN CACAUD, citizen of the French Republic, residing at 6 Avenue Vaulan, Toulon, Department of Var, France, have invented certain new and useful Improvements in Hydraulic Transmissions, of which the following is a specification. i

. My present invention relates to a hydraulic transmission comprising in combination a pump, a motor and conduits interconnecting the same to cause continuous flow of liquid between the said pump and motor, thepumpcomprising a rotary shaft, an eccentric on said shaft, and a plurality of pistons actuated by said eccentric and working in cylinders.

My transmission is intended to allow the utilisation of the power of a driving shaft, revolving at constant speed. or at definitely varying speed, upon a driven shaft, the speed of which can be variedaccording to the resistance opposed to the driving power VThe output 'of' the pump is regulated by varying the eccentricity of said pump; to that end, the eccentric actuating the pistons of the pump comprises two eccentric membersof which one is fixed on the driving ,shaft and the other rotatably movable relatively to the first, the relative rotation of these two eccentric members affording the resultant eccentricity desired.

This movement of relative rotation ofthetwo -eccentric members of the pump is obtained automatically in accordance with the variation .ofload of the motor, in such a way that the eccentricity of the pumpalways :assumes the .Value required to overco'me the resistance of the motor.

-for automatically varying the eccentricity of the pump.

I the The motor may be similar to the pump,

fortthe distribution.

As shown in Figures 1 and 2, an eccen- 55 I tric e is keyed upon a shaft a revolving about an axis o at constant speed; upon this eccentricvthere is mounted a ball bearing b, the outer face of `which is secured to af crown d carrying radially a suitable num- I ber of pistons p, having the same diameter and with their axes passing through thev 'centre 01 of the eccentr1c e.

Upon these pistons p are lmountedthe cylinders o, the ends of which are enlarged to form feet c1 arranged at right angles to the axes of the cylinders and adapted to move between vthe plane surfaces of fixed slide-ways and covers g g1; -these slide-Ways, form a vregular polygon having for centre the axis o of the shaft a around which the eccentric e revolves, the number of sides in polygon being equal to the number of pistons p.

It is known that if the shaft a revolves, carrying with it the eccentric e, and if the crown d is compelled to describe a translatory movement in which any straight line connected to this crown d must remain a parallel to itself, any point p1 upon a piston 80 p integral with this crown will describe a circle of radius equal to o o1, about a fixed centre g such that p? is parallel to 0 01. This known princi de is carried into effect in the present case, because the axes of '85 the cylinders c, guided by I the slide-ways g g1, arealways parallel to the same direction; the crown d 4therefore"describes the defined circular movement of translation.

The extremity p1 of each piston describes 90 its circle by compelling its c linder c to move upon its slide-way i?, the atter movement being identicalto t at of aslide valve set at advance; it is at its mid-travel osition when the piston is at the'end o its 95' stroke.- .This movement can thus be utilised Consequently if t. is anorifice or port in the head of the cylinder, fm, and n two other orices. formed in the slide-way g, the first .100 of which communicates with a reservoir of liquid not subject to pressure, and the second with a reservoir of liquid under pressure,A it will be seen that the piston-p draws in li uid through the orifice m and forces it out. t rough the orifice fn.; the same will a ply-for each of the-pistons with the sce difference that the suction and delivery are ylie on the side of the straight line o o1 in the direction of movement are on the delivery stroke, the others being on the suction stroke. i

There has thus been formed arotary ump without a special distributing slide va ve. v

` M, each one of which comprises a series'of pistons p, slidable in the cylinders c, the closed ends of which cylinders form distributing slide valves, by means of their sliding movement between the slide-ways g g1.

The parts m and n of the pump P are respectively connected to headers u u1, and the parts lm and n of the motor M to headers o, c1. The header u is connected to a -tank r not under-pressure, and the header u1 to a tank 1'?, under pressure connected to the header lv1 and the tank 'rl to the header '0.

The eccentric E, with center atvo, of the motor M, is fixed to the driven shaft A, turningabout axis O.

he eccentric of the pump P, which is fixed to the driving shaft D, comprises two eccentric elements (see Fig. 4) the tir-st of which, e1 is keyed to the drivingshaft D, and has an eccentricity o o1 equal to one half of the maximum necessary. Around this eccentric there is revoluble a second eccentric e2, of which the centre 02 is such that when o a1 and o? are in al straight line, o2 o is equal to twice o o1, the total eccen; tricity in these conditions being o o2. If the eccentric e2 is revolved around the eccentric c1, the centre 02 describes a circle around 071; to each position of the eccentric e2 there corresponds a varying total eccentricity, which will be nil when the eccentric c2 has turned tricv c1.`v l

It suices therefore, in order .to va the. eccentricity, to revolve the eccentrlc' e2 around .the eccentric e1 `by the desired amount. To automatically produce a relative rotary movement of the Vtwo eccentric elements through 180 around the eccen- Ye1, e2, so as to assure, at all time, 'a resulting V- eccentricity corresponding to the value of the charge of the motor, the following arrangement isused. Between the eccentric elements e1, e, (Fig. 4) is a space l, and a slide valve f, separating this space into two parts, the vane being guided in the'eccentric e2 so as to. be ableto withdrawr into the same.

The reaction'of the pump pistons `tends constantly to return the eccentric e2 to the position of maximum eccentricity; if then by eccentric e2 will tend to revolve in relation to the eccentric e1 according to the value of the pressurev thus conveyed, and thesectional area corresponding to the length ZL Z2 of the vane projecting into the cavity Z.

The shape of the cavity Z and the value ot the pressure may be combined in such a Way that to any given pressure of delivery from the pump'there will correspond a state As represented in Fig'. 3, the hydraulic transmission includes a pump P and a motor of equilibrium of the eccentric e2 in relatior to the eccentric el, with the corresponding resultant eccentricity.

In particular, if equilibrium exists for-the 'minimum resistance, with the maximum ecf centricity o2, o, and a pressure within the space f2 such that this pressure is that of the delivery, less a fixed amount, this pressure will -increase proportionally more rapidly than the; deliverypressure; consequently, when this latter increases, the eccentric e2 will revolve and the useful area of the vane decreasing as a result of the shape of the cavity,there will be established a p0-v Y sition of equilibrium of e2 with a resultant eccentricity whichV can be determined in advance.

In this way variation of the speed ofthe accordin What ' driven member will take .place automatically to the resistance. claim 1s:

, 1. A hydraulic transmission apparatus in' a motor,

cluding,'in combination, a pump conduits connecting the pump and motor to cause continuous liquid low between the said pump and motor, said pump comprising a rotary shaft, an eccentric on said shaft, a plurality of pistons actuated by said eccentric, cylinders in which said pistons work, the eccentric comprising two eccentric members having different centers, of which one is fixed on the said rotary shaft and the `end, and means for conveying into this space, a liquid under pressure to rotate the movable eccentric member relatively to` the fixed eccentric member, for the purpose described,

2. A hydraulic transmission vapparatus including, in combination, aA pump, a motor, conduits connecting the pump and motor to cause continuous liquid flew between the said pump and motor, said pump comprising a rotary shaft, an' eccentric -on said shaft, a pluralit of lpistons actuated by said eccentric, cylin ers in which said pistons work, the eccentric comprislng two eccentric members having different centers, and of which one isxed on the said rotary shaft andthe other rotatably. movable relatively to the first, and parts fast with the fixed ec centric member and bounding at one I'end a space of variable sectional area provided between the said eccentric members, a slide member guided in the movable eccentric member and bounding said space at the` other end, and means for conveying into saidspace a liquid under a pressure proportional to the delivery pressure of the pump to rotate the movable eccentric member relatively to the fixed eccentric member, for the purpose described.

3. ln a hydraulic transmission as claimed 'in claim 1, an eccentric collar positioned Aon ports connected to the suction and vdelivery conduits of the pump, and each of said cylinder ends having a port adapted to cooperate with the said ports to control the suc-I tion and delivery of the said pump.

4. In a hydraulic transmission as claimed.,

in claim 2, an eccentric collar positioned on the variable eccentric comprising the two eccentric members, the pistons of the pump being radially fixed upon said eccentric collar, a stationary regular polygon having plane sur-faces and having its center upon the axis around which the eccentric revolves, said plane surfaces constituting slide-ways for the ends of said cylinders, and having ports connected to the suction and delivery conduits of the pump, and each of said cylinder ends having a port adapted to cooperate with the said ports to control the suction and delivery of the said pump.

ln testimony whereof I have signed my name to this specification. K

MARCEL JEAN BENJAMIN CACAUD.

Witnesses:

JULE's LARnoNc, k PAUL PAOLI. 

